Thread-grinding machine



Feb 28, 11928;

J. BATH THREAD GRINDING MACHINE 27, 1921 6 Sheets-Sheet 1 Mia- 2648 Feb, 28, 1928. 1,660,468

J. BATH THREAD GRINDING MACHINE Original-Filed Dec. 27, 1921 6 Sheets-Sheet 2 m y Ma /W Feb. 28, 1928.

J. BATH THREAD GRINDING MACHINE 6 Sheets-Sheet 3 orignal /dfm J. BATH THREAD GRINDING MACHINE Feb. 28, 1928.

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Feb. 28, 1928.4 6 I 1,660,468

J. BATH THREAD GRINDING MACHINE Original Filed Dec. 27

Feb. 28, 1928.

J. BATH THREAD GRINDING MACHINE Original Filed Dec. 27, l

S'Sheets-Sheet 6 A ANQ Patented Feb. 28, 1928.

UNITED STATES PATENT ()FFICE.

JOHN BATH, OF WORCESTER, MASSACHUSETTS.

THREAD-GRINDING MACHINE.

Application filed. December 27, 1921, Serial. No. 524,817. Renewed August 1, 1927.

y This invention relates to a machine particularly designed for grinding the threads 01']? taps, thread gages or other similar arti- 6 It is one object of my invention to provide a thread grindin machine and a method of using the same y which the grinding operation may be made substantiall continuous during the travel of the grin ing wheel in both directions. With this object in view, an important featureofmy invention relates to the provision of an improved device for engaging and driving the work, said device being capable of definite angular adjustments to compensate for back lash and for other desired purposes.

A second ob ect of my invention is to provide a machine in which the Work spindle is directly driven and in which the lead screw for the grinding wheel is positively driven from the spindle.

An important feature of my invention relates to the provision of a plurality of interchangeable master lead screws by which threads of different pitch may be ground.

Other features of my invention relate to improved nteans for accurately forming and dressing the face of the grinding wheel, to means for accurately determining the amount of back lash in the machine, to an improved table adjustment, both angularly and longitudinally, to an arrangement for distributing the wear on the lead screw and for adapting the machine to operate on taps having shanks of different lengths, to an improved spindle setting device, andto arrangements and combinations of parts which will be'hereinafter described and more particularly pointed out in the appended claims. v

A preferred form of my invention is shown in the drawings, in which Fig. 1 is a plan view of my improved machine;

Fig. 2. is a horizontal sectional View of the work driving head;

Fig. 3 is a front elevation of the wheel head;

Fig. 4 is a plan view of the work table and certain parts carried thereby;

Fig. 5 is an end view of the work table;

Fig. 6 is a detail sectional plan view of the mechanism for angularly adjusting the table Fig. 7 is a front elevation of the devices for longitudinally adjusting the table;

Fig. 8 is an end elevation of the face plate and work driving attachments;

Fig. 9 is a sectional elevation taken along the line 99 in Fig. 8;

Fig. 10 is a partial plan view looking in the direction of the arrow 10 in Fig. 9;

Figs. .11, 12, 13, and 14 are detail sectional views taken respectively along the lines 11-11, 1212, 1313, 1414, of Fig. 8;

Fig. 15 is a plan view of certain parts of the machine, illustrating the method and apparatus by which the amount of back lash is determined; Fig. 16 is a detail sectional. elevation taken along the line 1616 in Fig. 15;

Fig. 17 is an' end elevation looking in the direction of thearrow 17 in Fig. 15;

Fig. 18 is a partial plan view of certain parts, including my improved wheel dressing device, the tall stock being shown in section; 1

Fig. 19 is a detail plan view illustrating the use of the wheel dressing device;

Fig. 20 is an end elevation of the wheel dressing device, and showsthe auxiliary tool for dressing the face of the wheel;

liig. 21 1s a plan view of the auxiliary too I Fig. 22 is an end view of the tail stock, looking in the direction of the arrow 22 in Fig. 18, and j 1 Fig. 23 is a detail front elevation, looking in the direction of the arrow 23 in Fig. 18.

Referring to the drawings, I have shown a thread grinding machine comprising a base or bed 30, a work table 31, a head stock 32, a tail stock 33, a'wheel table 34, a wheel carriage 35, and a wheel head 36. The details of construction of the wheel head and carriage are not set forth in detail herein, as they are substantially shown and described in my prior application, Serial No. 411,243, filed September 18, 1920.

For the purposes of this application, it is suflicient to state that the grinding wheel W carriage 35 may be adjusted toward and from the work by a hand wheel 43. (Fig. 1.)

The wheel table 34 is mounted to slide longitudinally on guide-ways 44 and 45 (Fig. 1) formed on the base 30, the table being moved longitudinally by a lead screw 46 mounted in a bearing 47 and threaded into a nut 48 (Fig. The nut-48 is slidable between the guide-ways 49 and 50 and may be secured in adjustable longitudinal position therein by clamping bolts 51. The nut 48 is preferably provided with a removable inner sleeve or bushing 52 held within the nut by clamping bolts 53 and easily removed ,and re laced. Locking collars 54 and 55 are rovi ed for taking up all end play in the bearing 47.

With this construction, it is evident that the positionof the nut 48 in the table 34 may be changed from time to time, thus bringing the wear upon different portions of the lead screw and avoiding the disadvantage which is often encountered of concentrating the wear of the screw at one limited portion of its length. The lead screw 46 is provided with a gear 56 meshing with an idle or intermediate gear 57, which in turn is driven by a gear 58, mounted on the work spindle 60. The intermediate gear 57 is mounted upon a plate 59 which may be adjusted on the end of the base 30 to 'mesh with gears 56 and 58 of different sizes when desired, but I contemplate the use of very few change gears, as

' I consider it more desirable to provide a separate master or lead screw 46 and bushing 52 for each different pitch to be ground.

, The work spindle 60 is supported in conical bearings 61 and 62 in the head stock 32 and the usual lock nuts 63 are provided for taking up end play in the bearings. A bevel gear 64'is preferably mounted on the spindle 60 and is engaged by a bevel pinion 65 mounted ona short shaft extending forward through a bearing 66 and having a hand wheel 67 at its front or outer end.

This hand wheel is used for making limited angular adjustments of the work for purposes to be hereinafter described and may be provided with suitable graduations to be read in connection with an index or pointer 68, indicating the exact amount of the angular adjustment of the work.

The work table 31 rests upon a flat finished surface of the bed 30 and is provided with a longitudinal groove or guide-way 70 (Fig. 5) closely fitting a pair of guide-blocks 71 and 72 (Fig. 4). The block 71 is pivoted at 73 to the base 30, near the left hand end of the table 31. The block 72 is pivoted at 74 to a slide 7 5 mounted for limited transverse.

movement in a recess 76 in the upper face of the base or bed 30. Adjusting screws 77 and 78 are provided by which the transverse pcsition of the slide and block 72 may be accurately adjusted. The table 31 is acjustments, a bracket or arm 83 is secured to the edge of the table 31 and a pair of adjusting screws 84 and 85 are threaded in bearings 86 fixed to the side of the base 30. By turning the screws 84 and 85, limited longitudinal adjustment of the table may be secured. The parts after adjustment may be securely held from displacement by tightening the binding screws 87 (Fig. 4) to bind the screws 84 and 85. This longitudinal adjustment is used merely for aligning the wheel WV with the thread groove of the tap or screw to be ground and the movement does not exceed a small fraction of an inch in extent.

The preferred construction of the tail stock 33 is best shown in Figs. 18 and 22. The tail center 90 is mounted in a spindle 91, slidable in suitable bearings in the tail stock 33. Aspring 92 is disposed in a recess in the spindle between a shoulder 93 thereof and a cap 94 threaded on the end of the tail stock. The spring 92 yieldingly presses the tail center towards the work.

A hand lever 95 (Fig. 18) is mountedon a fixed pivot 96 and is provided with a lug or arm 97 extending inward to engage a shoulder 98, formed in the side of the spindle or slide 91. The handle 95 thus constitutes means by which the tail spi'ndl'e', n1ay be withdrawn against the pressure of the spring 92 to release the work.

A? cam member 99 may be rotatably secured on the cap94 by a screw 100 extending through a segmental slot 101 formed in the periphery of the cam member. The cam member 99 is also provided with a handle 102 and with a notch 103. When the handle 102 is swung forward the cam'engages the handle 95, depressing the same and withdrawing the tail center. If the cam is ad vanced to its full extent, the handle 95 is received in the notch 103 and the parts will be held in this position until thereafter released by the operator.

In the operation of my improved grinding machine, I use work driving devices of novel construction which devices will now be descrlbed. particular reference being madeto Figs. 9 try-14. I

The usual face plate 105 is threaded on the end of the spindle 60 and is provided with a hub or extension 106 on which is mounted a ring 107 supporting a pair of work driving dogs 108. These dogs are radially adjustable on the ring 107 and are secured thereto by binding screws 109.- The inner ends of the dogs are shaped to receive and engage the shank of a tap or other article to be ground.

The ring 106 is flanged and is held against the face plate by anouter ring 110 secured to. the face plate bybinding screws 111 and 112 (Figs. 8 and 14). A slot 113 extends nearly around the ring 110 and the binding screw 111 is shown as extending through this slot, while the screw 112 extends through a hole in the ring 110 between the ends of the slot 113. -A series of tapped holes 114 may be provided in the face plate to receive the screws 111 and 112.

Segmental blocks 115 and 116 (Figs. 8 and 12) are provided with curved ribs or projections"117 (Fig. 13) fitting the segmental slot 113.. These blocks are secured in angular'adjusted position by clamping bolts 118 and nuts 119 (Fig. 12). A spring handle 120 is secured toeach. block 115 or 116 and is provided with a spur 121 engaging notches 110 formed at the' outer edge of the ring 110.

A similar spring handle 122 is secured to the inner ring 107, this handle being provided with a socket or recess 123 adapted to receive pins or studs 124 formed on the ends of tlie'bolts 118 which secure the blocks 115 and '116 in position. Stops 125 and 126 (Figs. 8 and 11) are also slidable in the slot 113 of the ring 110 and may be clamped, in position as will be hereinafter described.

In the operation of my improved machine, the blocks 115 and 116 are so located that the movement of the handle 122 from one pin or stud 124 to the other will cause an angular movement of the dogs 108 exactly equal to the back lash .in the connections between the work spindle and the grinding wheel table. The extent of this angular adjustment of the work required with a particular set-up of the machine is determined experimentally by use. of the indicating device shown in Figs. 15 to 17.

An arm 130 (Fig. 15) is fixed on the lead screw nut 48 and extends forwardly and upwardly to at position for engagement by the short end of an indexlever 131, pivoted at 132 on a stand 133. 'The stand is adjustably secured to the head stock 32 by a clamping bolt 134. A1 lock plate 135 is slida-bly mounted in guideways 136 on the head stock 32 and may be secured in adjusted position by a clamping belt 137. An index or zero line is formed on one of the guide-ways 136 as a reference mark for the index-lever 131.

In order to determine the exact amount of backlash in the connections between the spindle and the wheel table, the spindle is moved in the direction in which it has been rotating until the handle 122 of the dog supporting ring 107 is aligned with the jaws of the lock plate 135. This plate is then advanced inits guide-ways 136 until it releases the handle from the pinor stud on which it has been seated and looks it from further angular movement. The stand 133 of the index lever or pointer 131 is then adjusted so that the rear end of the pointer will be pressed against the arm 130 by the pointer spring138, while at the same time the end of the pointer co-incides with the zero mark on the guide-way 1 36. v

The spindle 60 is then turned backward or in the opposite direction to that in which it has been rotating until the lead screw 46 begins to move' the nut 48, such movement being instantly indicated by movement of the pointer 131. The second sliding block 115 or 116 is then moved to bring its stud 124 into alignment with the recess in the handle 122, in which position it is then secured.

VVith the positions of the blocks 115 and 116 thus accurately located, it is merely necessary to swing the handle 122 from one stud 124 to the other, when the direction of the table feed is reversed to cause the grinding wheel to accurately follow the thread in both directions of table feed. .If it is found that the wheel when thus adjusted engages slightly harder on one side than on the other, one of the blocks 115 or 116 may be further adjusted by moving its handle 120 one or more notches along the ring 110.

When adjustment is once made for a particular set-up of the machine, no further attention is necessary beyond swinging the handle 122 from one stud 124 to the other at each end of the wheel travel. The output the usual idle return feed of the grinding wheel is entirely avoided.

When grinding certain types of thread,

such as the Acme thread, it is sometimes desirable to feed the wheel sideways to widen the thread groove. The stops 125 are then used to preserve the original setting so that the slides 115 or 116 may be moved the required number of notches sideways to widen the thread and may then be returned-to their original positions when a new thread is to be ground and widened.

It has been found desirable to drive the work spindle by a belt pulley of fairly large diameter as this type of feed reduced the chatter or other irregular movements of the work, and I have shown in Fig. 1 a cone pulley 140 by which the speed may be varied,

tain angular amount relative to the face 100 of the machine is thus greatly increased, as

I have shown a wheel dressin device by which the wheel maybe dresse to restore the. face of the wheel to its original sha e and position. For this purpose, I provi e a shaft 141,' (Fig. 18) one end of which is pivoted in the headstock 32 and the other end of which is supported i'n-a bearin 142 (Fig. 23) mounted on the base 30. A hi ing collar 143 (Fig. 18) and a threaded bushing 144 are provided for taking up end play in the shaft 141. A guide Plate 145 is clamped to the shaft 141 and may be secured in any desired longitudinal position thereon by a binding screw 146. A support 147 (Fig. extends downward from the plate 145 and is provided with an adjusting screw 148 adapted to engage theinclined face of the work table 31, .supporting the guide ably mounted. The bloc moved the point 155 ma be advanced to engage the plate in operative position;

. The g'lllde plate'145 is provided with a pair ofguide-ways 149 and 150, equally inclined with res ect to the plane of the wheel W and'the i e plate is also provided with a third gui e-way 151 extending parallel to the axis of the wheel W. A diamond point grinding wheelto cut when moving in both 152 -(Fi 19) is adjustably mounted in the plane 0 a diagonal of the square slide 153-.

In dressing a wheel, the'guide-plate 145 is first adjusted longitudinally until it is centered with respect to the wheel W. The slide 153 is then moved back and forth along one ofthe ide-ways 149 or 150 to dress one side of t e'wheel and the slide is then reversed and moved along the other guide-'way to dress the op osite side. of the wheel, the wheel beinged forward slightly if. neces- "sary during the wheel dressing operation.

It is often desirable to true up the extreme ed e of the wheel or'to provide a nar row flat face thereon and for this purpose I provide the auxiliary slide bloc 154 in which a second diamond [Lint 155 is adjust- 154 is provide with a V "shaped rojection 156 fitting the guide-way 151. be block can, thus be parallel to the axis of the wheel 'and edgf of the whee as desired.

' y wheel dressing device lsshown 1n the drawings in operative po'sltion, but when not in use it may be swun forward and down- Avard without removal from the machine.

' The device is thus always convenient for use when desired. In Fi 4 I have shown a support 160' upon whic 1 a tap may be placed "in convenient position for'the operator when changing the work.

" Havin 'thus described my invention and indicate the method of operation thereof,

it will be seen that my improved machine and method of using the same enable me to secure greatly "increased production and improved results in this line of work. By'setting the blocks on the face plate to-correspond to the back lash of the machine, I'am 1,aco,4es

able to continue the grinding j o eration dur ing the movement of the gun ing wheel in turbing the adjustmentof the parts, so that the sharpened wheel is immediately available for use without readjustment of the machine.

The hand Wheel 67 on the heads'tock 32 is particularly useful in advancing the spindle 60 to brin the cutting face of the teeth of a tap to a orizontal 'osition when setting up t e machine, so t atthe work table may be adjusted to accurately center the wheel in the thread of the tap. Where the taps are accurately threaded and .the cor? responding face of each tap ismarked by some symbol as B 1n Fig. 9, I find-it possible to successivelyinsert a series of taps in the machine and continue the grinding operation without any resetting or adjustment of the machine for each different tap.

An incidental advantage of using the rected or elimianted.

While I have described theadjustment for back lash as being made between the work and its driving spindle, my. inventionan'd tion is not limited in its broader aspects to ingl device or to a particular. location thereof an my invention broadly contemplates the use of any suitable adjusting deviceby which such correction may be made at any available point between the work and the grinding of a second divisional application Serial filed by me Decem or 14, 19Q5.

thus described my invention, it

Having particularlymy im roved method of opera- 1 d the provision or use ofa particular adjustwill be evident that chan es and modifications can be'made therein those skilled in the art within the spirit an scope of m mvention as set forth inthe clauns, and do not wish to be otherwise limited to the details herein disclosed, but what I claim is :--f 1. A thread. grinding machine COIHPIlSlIlg a grinding Wheel, awork rotating member,

connected means to rotate'said member and move said wheel axially of the work, and means to adjust said connections by a predetermined amount to compensate for back lash in said connections when the direction of motion isreversed, said grinding wheel being operative to grind threads when the work is rotatin in eitherdirection.

2. In a threa grinding machine, a grinding wheel, a work rotating-member, connections between said wheel and member, and a device'to indicate .the initial movement of the grinding wheel axially relatively to the Work when the direction of wheel travel is reversed.

3. In a thread grinding machine, a grinding wheel, a work rotating member, connections between said wheel and member, and a device to indicate the initialinovement of 'the grinding wheel axially relatively to the work when the direction of wheel travel is reversed, and means-to angularly adjust the work relative to the work rotating member to compensate for said axial adjustment of the wheels i 4. In a threadtgrinding machine, a head stock, a work supporting spindle, a work driving member mounted thereon, means on said head to release said member from said spindle and to hold said member in fixed .position, a grinding wheel, a support therefor,'connect1ons between the spindle and the wheel support, and a multiplying device to indicate initial'movement of the wheel support when the back lash of said connections is taken up by reversed, rotation'of said spindle.

5-. In a thread grinding machine, a head stock, a work driving spindle mounted therein, power means to rotate said spindle, a short shaft extending forwardly through the front of said head stock and geared to said s indle, and means on the front end of said s aft by which said spindle may be angularly adjusted.

6. In a thread grinding machine, a head stock, a work driving spindle mounted therein, power means to rotate said spindle, a short shaft-mounted in said headstock and geared to said spindle, said shaft extending forwardly through the front of said head stock, and a hand wheel on said short shaft having graduations co-operating with a fixed index to indicate angular adjustment of said spindle. i

7. In a thread grindinginachine, a work 'table, a tail stock, a tail center, a slidable support therefor, means to yieldingly ad- Vance. said support and center to operative position, means to withdraw said support, and a manually operable cam to actuate said means'to withdraw said support and center and to lock said center in withdrawn position.

8. In a thread grindin'g machine, a work a table, a tail stock, a tail center, a slidable support therefor, means to yieldingly advance said support and center to operative position, and means to withdraw said support and to retain said support ininoperative withdrawn position.

9. In athreadgrinding machine, a lead screw, a wheel-table, and .anut for said screw, said'nut being adjustable on said table axially of saidscrew.

10. In a thread grinding machine, a Wheel.

12. In a grinding machine, a bed, a work supporting table, means to guide said table longitudinally on said bed,-andmeans to adjust said table longitudinally, said means comprising a bracket on one of said parts and co-operating adjusting screws reversely mounted on the other part and engaging opposite sides of said bracket.

13. In a thread grinding machine, a bed, a work supporting table mounted thereon,

said table having a longitudinally extending guide-way in its lower face, a block pivoted to said bed and fitting saidguide-way at one end of said table, a; second block fitting said guide-way at the opposite end of said table, a slide to which said second block is pivoted,

and means to adjust said slide in said bed transversely of'said table. J

In testimony whereof I have hereunto aflixed my signature.

JOHN BATH. 

